1. Field of the Invention
The present invention relates to an optical disk player which records and reproduces data in optical disks such as CD, DVD, and so on, for example.
2. Description of the Related Art
A conventional optical disk player records and reproduces data in an optical disk by irradiating a light, which is output from an optical pickup unit, on the optical disk with rotating the optical disk by a disk drive unit. The optical pickup unit has a light emitting device, a light receiving device, and so on in a case, so that it outputs a light, which is emitted from the light emitting device, from a light hole formed on the case and also receives a light, which enters from the light hole, by the light receiving device. The optical pickup unit is held in a rack which moves with rotation of a pinion, and moves in a radial direction of the optical disk (that is, a seek operation is performed) with the rack according to the movement of the rack caused by the rotation of the pinion by a driving force of a motor.
In this type of the optical disk player, a double rack having two rack plates which overlap each other is applied as the rack to improve feed accuracy of the optical pickup unit, so that a backlash between the pinion and the rack is prevented. As the double rack, a composition shown in FIGS. 5A and 5B and FIGS. 6A, 6B, and 6C is well known.
A rack 100 in FIGS. 5A and 5B and FIGS. 6A, 6B, and 6C comprises two rack plates, that is, a fixed rack plate 101 and a movable rack plate 102. The fixed rack plate 101 is formed to be integral with a case 104 of an optical pickup unit 103 and is supported by guide members, that is, a guide bar 105 and a guide rail 106 to be movable in a tooth row direction of the fixed rack plate 101. The movable rack plate 102 is mounted on a top of the fixed rack plate 101 so as to be able to slide in a moving direction of the fixed rack plate 101. The optical pickup unit 103 outputs and lets in a light from a light hole 107 which is provided in an upper surface of the case 104.
On the fixed rack plate 101, projecting members 111, 112, and 113, which project from an upper surface of the fixed rack plate 101, are disposed along the moving direction of the fixed rack plate 101, and in contrast, in the movable rack plate 102, guide slots 121, 122, and 123 are disposed along a tooth row direction of the fixed rack plate 102. The projecting members 111, 112, and 113 on the fixed rack plate 101 are slidably inserted into the guide slots 121, 122, and 123 in the movable rack plate 102, and thus, the movable rack plate 102 is mounted to be able to slide in the moving direction of the fixed rack plate 101.
On the fixed rack plate 101, a locking portion 115, which projects from a side surface of a supporter 114 provided on the upper surface of the fixed rack plate 101, is provided, and in contrast, on the movable rack plate 102, a projecting portion 124, which projects from a side surface of the movable rack plate 102, is provided. The locking portion 115 on the fixed rack plate 101 is located above the projecting portion 124 on the movable rack plate 102 and also locks slidably the projecting portion 124, so that the movable rack plate 102 is held not to be detached from the fixed rack plate 101.
On the movable rack plate 102, a projecting member 125, which projects from an upper surface of the movable rack plate 102, is formed, and a spring 130 is provided between the projecting member 112 on the fixed rack plate 101 and the projecting member 125 on the movable rack plate 102. The fixed rack plate 101 and the movable rack plate 102 are engaged with a pinion 140 with compressing the spring 130 between the projecting members 112 and 125 (refer to FIGS. 6A, 6B, and 6C).
In the rack 100 having the composition described above, stretching force of the spring 130 allows teeth of the fixed rack plate 101 and teeth of the movable rack plate 102 to hold teeth of the pinion 140 tightly, thus the backlash between the rack 100 and the pinion 140 is prevented, and the feed accuracy of the optical pickup unit 103 is improved.
However, in the conventional optical disk player described above, the projecting members 111, 112, and 113 on the fixed rack plate 101 are slidably inserted into the guide slots 121, 122, and 123 in the movable rack plate 102, so that there are clearances between the projecting members 111, 112, and 113 and inner surfaces of the guide slots 121, 122, and 123 and between the supporter 114 and the projecting portion 124. Consequently, when the rack 100 moves with the rotation of the pinion 140, the movable rack plate 102 shakes in a horizontal direction (in a direction perpendicular to the moving direction of the rack 100) by the driving force of the pinion 140, and the inner surfaces of the guide slots 121, 122, and 123 hit the projecting members 111, 112, and 113, or the projecting portion 124 hits the supporter 114, thus a clatter occurs. This clatter is offensive to the ear.